page_title: Paleobiota of the Posidonia Shale
section_title: Annelida
hierarchical_section_title: Paleobiota of the Posidonia Shale / Invertebrata / Annelida
caption_attribution_description: English: Glomerula gordialis from the Upper Cretaceous of Germany
context_page_description: The Posidonia Shale or Posidonienschiefer Formation is a geological formation of southwestern Germany, northern Switzerland, western Czech Republic, northwestern Austria, southeast Luxembourg and the Netherlands, that spans about 3 million years during the Early Jurassic period. It is known for its detailed fossils, especially sea fauna, listed below. Composed mostly by black shale, the formation is a Lagerstätte, where fossils show exceptional preservation, with a thickness that varies from about 1 m to about 40 m on the Rhine level, being on the main quarry at Holzmaden between 5 and 14 m. Some of the preserved material has been transformed into fossil hydrocarbon Jet, specially wood remains, used for jewelry. The exceptional preservation seen on the Posidonia Shale has been studied since the late 1800s, finding that a cocktail of chemical and environmental factors let to such an impressive conservation of the marine fauna. The most common theory is the changes on the oxygen level, where the different anoxic events of the Toarcian left oxygen-depleted bottom waters, with the biota dying and falling to the bottom without any predator able to eat the dead bodies.
caption: Example of Glomerula specimen
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